1. Field of the Invention
The present invention relates to a multi-color display system, and particularly to a multi-color display system using a liquid crystal display panel or the like.
2. Description of the Prior Art
In a conventional multi-color liquid crystal display system, each of visual information dots is composed of four liquid crystal cells with red, blue, green and white filters respectively provided thereon. Eight colors can be presented by combination of ON-OFF controls of the red, blue and green liquid crystal cells, and additional eight colors can be presented by addition of ON-OFF control of the white liquid crystal cell to each combination of ON-OFF controls of the red, blue and green liquid crystal cells. Thus, sixteen colors are available in total.
One of such conventional multi-color liquid crystal display systems is described below with reference to FIG. 10,
FIG. 10 shows one example of a liquid crystal panel used in the conventional multi-color liquid crystal display system. It has a display area of 640.times.400 dots. One dot is composed of 2.times.2 liquid crystal cells, and therefore the panel has 1280 (=640.times.2) cells aligned in each horizontal line and 800 (=400.times.2) cells aligned in each vertical line. As described above, eight colors can be presented by combination of ON-OFF controls of the red, blue and green liquid crystal cells, and additional eight colors can be presented by addition of ON-OFF control of the white liquid crystal to each combination of ON-OFF controls of red, blue and green liquid crystal cells, thus providing totally sixteen colors.
A similar multi-color representation is described in Japanese Laid-open Patent Application No. 63-210888.
The above described prior art requires liquid crystal cells four times the number of the display dots, causing an active matrix type liquid crystal display using thin film transistors to suffer from reduction of yield due to the increase of the number of thin film transistors, and accordingly unit cost of the liquid crystal display panel is increased.
Also, a twisted nematic type liquid crystal will suffer from decrease in display duty cycle of each display line, which decrease lowers the contrast in display.